New sauropod material from the Late Jurassic part of the Shishugou Formation (Junggar Basin, Xinjiang, NW China)

In April 2006, three new dinosaur localities were discovered in the upper part of the Middle to Late Jurassic Shishugou Formation within "Dinosaur Valley", a classic Junggar Basin locality for Jurassic vertebrates. Recovered bones comprise cervical vertebrae of an adult and a juvenile sauropod and several sauropod forelimb elements. The vertebrae show several affinities to Mamenchisaurus, but a generic assignment cannot be undertaken considering the fragmentary nature of the material and the uncertain status of taxa assigned to the genus Mamenchisaurus. Comparisons make it likely that they are more closely related to Mamenchisaurus and Omeisaurus than to other eusauropods and Euhelopus. All vertebrae expose an accessory lamina at the vertebral centrum, which might also be present but remained undescribed in species of Mamenchisaurus. Indications in the forelimb elements, such as humerus, ulna, and pollex claw, do not allow a determination of the taxa, although there are no distinct differences to Mamenchisaurus. The remains are important because of their extreme size, including potentially the first recognized juvenile remains of a Mamenchisaurus relative, and demonstrate further evidence for the occurrence of non-neosauropod eusauropods in the Junggar Basin.